A guide-rail assembly is known from U.S. Pat. No. 3,784,358 that comprises a succession of rail sections each formed by a relatively long central subsection and a pair of relatively short end subsections that flank the respective central subsection. Horizontal pivots extending transverse to the longitudinal extension direction of the rail formed by the rail sections interconnect each of the end subsections with the respective central subsection. Limitedly flexible rods are provided at the joints between adjacent rail sections, with each rod having one end anchored in the central subsection of one rail and an opposite end anchored in the central subsection of the two intervening end subsections of the respective rail sections. These rods permit limited flexing of the rail sections and set outer limits to the longitudinal displacement of the rail sections away from each other.
Normally each rail section carries a respective trough section of a chain conveyor. The trough sections have effective longitudinal lengths that are somewhat greater than the effective longitudinal lengths of the respective rail sections, so that the ends of these trough sections abut whereas the ends of the rail section do not.
A chain for cutter-loader, constituted either as a plow or planer, has an upper reach extending through an upper longitudinal passage formed through the rail sections, and a lower reach extending in a lower passage similarly formed through the succession of rail sections. This chain pulls the cutter-loader longitudinally along the rail. A conveyor chain has an upper reach lying in the trough formed by the trough sections and carrying a plurality of conveyor-scraper elements, and a lower reach underlying the trough. Both of these chains exert with their tensioned stretches, normally their upper stretches, considerable longitudinal forces, whereas their return stretches, which are normally their lower stretches, are somewhat loose.
These forces are normally transmitted to the abutting ends of the trough sections. As a result these trough-section ends are subjected to considerable longitudinal force, often capable of bending and deforming them at their ends. When the assembly lies on uneven ground, so that adjacent rail and trough sections are not perfectly in line with one another, the forces effective on the trough sections are considerable, and can often exceed their elastic limits so as to damage them. Similarly the forces effective on the chains can become so very great as to stretch or permanently damage them.